• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.221-224
• /
• 2008

We made densified wood pellet by hemp woody core as replacing wood resource. Hemp was separated into the bast fiber and the woody core by hot steaming treatment. The hemp woody core had a similar lignin content and carbohydrate composition with hardwood. Also, the hemp had a low ash content, which resulted in a low ash formation in pellet burning. Heating value of the hemp pellet had a very similar to the pellet made by hardwoods. The hemp woody core can replace hardwood for densified wood pelletmaking.

• Composites Research
• /
• v.20 no.3
• /
• pp.55-62
• /
• 2007

Interfacial evaluation and durability of Jute and Hemp fibers/polypropylene (PP) composites were investigated. Moisture content of various treated conditions were measured by thermogravimetic analyzer (TGA). After boiling water test, mechanical properties and IFSS between Jute, Hemp fibers and PP matrix decreased. On the other hand, work of adhesion increased due to swelled fibril by water. Surface energies of Jute and Hemp fibers before and after boiling water test were obtained using dynamic contact angle measurement. IFSS was not always consistent with thermodynamic work of adhesion. In boiling water case, since Jute and Hemp fibers could be swelled by water, surface area and moisture infiltration space increased. Environmental effect on microfailure modes of Jute or Hemp fibers and Jute or Hemp fibers/PP composites were obtained by observing via optical microscope and by monitoring acoustic emission (AE) events and their AE parameters. After boiling water test, unlike Hemp fiber, microfailure process of Jute fiber could occur due to low tensile strength by swelled fibril. In addition, AE events occurred more and AE amplitude and energy became lower than those of before boiling water test.

• Journal of Advanced Navigation Technology
• /
• v.19 no.3
• /
• pp.244-249
• /
• 2015

High-altitude electromagnetic pulse (HEMP) is generated from a nuclear burst at high altitudes above the Earth, the electromagnetic fields reach the ground nearly simultaneously with regard to the operation time of systems. The aim of this analysis is to inquire about HEMP characteristics and to analyze about effect in orthogonal frequency division multiplexing (OFDM) system. Specifically, HEMP characteristics are classified field sources, spatial coverage, time domain behavior, frequency spectrum and field intensities in this study. Bits error rate (BER) of the receiver with the software simulation is confirmed for the HEMP effect. Q-factor made a difference about interference duration by transfer characteristics of system. When Q factor is smaller, the recovery time from HEMP interference is short. To the contrary, if the Q factor is larger, the recovery duration is lasted longer by 300-600%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.8
• /
• pp.790-796
• /
• 2011

The system which is exposed in the impact range of High-altitude Electromagnetic Pulse(HEMP) may get serious damage because HEMP has a very large electric field value, a very fast rise-time, and so on. Electromagnetic analysis should be performed for signals coupled to the opening or cables of the system prior to derive the system design specifications in order to protect the system against HEMP adequately. In this paper, we analyzed the HEMP coupled signals for the coaxial cable which is generally used to transmit and receive video or RF signals and compared the coupled signal of the one wire with that of the inner conductor of a coaxial cable to confirm the decreased effect of HEMP by the shield. The coaxial cable is analyzed by the external and internal region of the shield separately. For the external region of the coaxial cable, general scattered equation was applied to calculate currents on the surface of the shield and for internal region of the coaxial cable, chain matrix algorithm is used. To verify this paper the analyzed results were compared the results of the existing paper and the two results have good agreements.

• Textile Coloration and Finishing
• /
• v.21 no.5
• /
• pp.10-15
• /
• 2009

A mixed bi-functional reactive dye has been applied to the cotton and the cotton/hemp blend and their dyeing and fastness properties were compared. The cotton/hemp blend exhibited higher exhaustion values and better build-up property than cotton, presumably due to the lower crystallinity. Hence, the reproducibility of dyeing of hemp is expected to be excellent. Fastness properties of reactive dyes on cotton and cotton/hemp blend are found to be almost identical. The results obtained suggest that hemp in cellulosic fabric could be used as an important alternative to universal cotton in cellulose fabrics.

• Journal of Satellite, Information and Communications
• /
• v.8 no.4
• /
• pp.6-11
• /
• 2013

In this paper, we explain the signal characteristics of HEMP and HEMP protection factors that affect the facilities are analyzed. We find the necessary elements of the physical facilities available for building. Shielding effects were measured by changing frequency and the distance of receiving antenna. Each measured value was compared to U.S. standard and measuring method was simplified. shielding effects were measured by three different conditions of shielding room. Find the difference between forward measurement and reverse measurement and factors which affects the measurement in shielding room.

• Advanced Composite Materials
• /
• v.16 no.4
• /
• pp.385-394
• /
• 2007

In this study, the effect of molding condition on the tensile properties for plain woven hemp fiber reinforced green composite was examined. The tensile properties of the composite were compared with those of the plain woven jute fiber composite fabricated by the same process. Emulsion type biodegradable resin or polypropylene sheet was used as matrix. The composites were processed by the compression molding where the molding temperature and its heating time were changed from 160 to $190^{\circ}C$ and from 15 to 25 min, respectively. The following results were obtained from the experiment. The tensile property of hemp fiber reinforced polypropylene is improved in comparison with polypropylene bulk. The strength of composite is about 2.6 times that of the resin bulk specimen. Hemp fiber is more effective than jute fiber as reinforcement for green composite from the viewpoint of strength. The molding temperature and time are suitable below $180^{\circ}C$ and 20 min for hemp fiber reinforced green composite. Hemp fiber green composite has a tendency to decrease its tensile strength when fiber content is over 50 wt%.

• Korean Journal of Plant Resources
• /
• v.21 no.3
• /
• pp.222-225
• /
• 2008

Chemical composition and enzymatic saccharification characteristics of hemp woody core were investigated by their chemical composition analysis and enzymatic saccharification with commercially available cellulases (Celluclast 1.5L and Novozym 342). Hemp woody core have higher xylan and lower lignin contents than its bast fiber. Based on hemicelluloses and lignin composition, hemp woody core is similar with hardwood biomass. However, cellulose was more easily converted to glucose than xylan to xylose and this trend was confirmed both hemp woody core and yellow poplar. Hemp woody core biomass shows higher saccharification than yellow poplar (hardwood biomass) based on cellulose and xylan hydrolysis. With easier enzymatic saccharification in cellulose and xylan, and similar chemical composition, hemp woody core have better biorefinery feedstock characteristics than hardwood biomass.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.10
• /
• pp.2331-2338
• /
• 2014

The HEMP threat may have acquired new, and urgent, relevance as the proliferation of nuclear weapons and missile technology accelerates of the North Korea, for example, is assessed as already having developed few atomic weapons, and is on the verge of North Korea already has missiles capable of delivering a nuclear warhead against South Korea. ITU K.78, K81 and IEC recommended its counter-measuring for the industrial facilities with navigation and sailing facilities in order to obviate the all of processor equipped system malfunctions from the EMP/HEMP but its simulation must only be done by the computer simulation which had studied on the 1960-1990 years USA/AFWL papers. This result has a significant activities to the South Korea being under the North Korea threat because all of HEMP related products was strongly limited for export. The HEMP cord which was developed newly by the KTI including the HEMP generation & propagation analysis, optimal shelter design tool, essential EM energy attenuation in multi-layered various soils and rocks and HEMP filter design tool. Especially, the least square fitting method was adopted to analysis for the EM energy attenuation in the soils and rocks because it has a various characteristics based on the many times field test reports.

• Food Engineering Progress
• /
• v.14 no.2
• /
• pp.99-105
• /
• 2010

Proximate composition of whole hemp seed, paste viscosity of whole hemp seed pellets, bulk density, color, compression force, water solubility and absorption index and bowl life of whole hemp seed flakes manufactured by extrusion process were determined to evaluate whole hemp seed as flake additive. Extrusion process conditions were 35% of moisture content and 90, 100 and 110$^{\circ}C$ of barrel temperature. Content of moisture content, crude protein, crude fat, crude ash from whole hemp seed were 5.67${\pm}$0.02%, 25.93${\pm}$0.16%, 28.21${\pm}$0.56% and 7.70${\pm}$0.08%, respectively. The pellets hemp seed at 100 or 110$^{\circ}C$ had higher paste viscosity as compared to those pellet at 90$^{\circ}C$. The bulk density values of all hemp seed flakes were between 0.24 to 0.43 g/mL, depending on the barrel temperatures. The hardness of flake increased with decreasing percentage of hemp seed in flakes. An increase in barrel temperature from 90$^{\circ}C$ to 110$^{\circ}C$ resulted in increase of WSI and decrease of WAI. The bowl life of hemp seed flakes was increased from 5.8 to 15.5 min with the decrease in percentage of hemp seed. The highest overall quality was showed in flake added with 20% of hemp seed.